Can my employer sue me for doing a bad job

I worked as a bookkeeper for an attorney for 10 years, he also had other businesses which I kept the books for. I quit in October and received a letter from his attorney last week . The letter states that I altered the books and did not do my work, also that I spent my days doing personal things - In the letter the attorney requests I contact my old boss within 30 days or they will sue me for my compensation and seek treble damages pursuant to the Florida Civil Theft statutes. I called the attorney and he said they can't get a handle of my work - that bank reconcilations were not done and that checks were not deposited. Also that he had to pay income tax on money he did not receive due to my poor bookeeping - They requested my help to try and resolve some of these issues - I said I would try but would like some release stating they were not going to sue me. He said they would not do that now and I was 1 step away from being sued. He said they knew I had not stolen anything but things are a mess. So my question is can he sue me - I did not steal anything and had no access to sign checks etc. He was basically lazy and did not review my work so I got lazy as well and did not do it properly, Can he sue me for any tax penalties for unfiled sales tax and/or payroll taxes payments I did not make - We also had an independent CPA - who reviewed my work, but did not really and trusted my numbers to be correct - Ethically I would like to help him, but what if I can't figure out what I did wrong?

wld emailed you privately